The present invention relates to video display bases and, more particularly to video display bases which are height adjustable.
The need for a height adjustable video display is well known. This need occurs because of the inherent difference between the level of a keyboard for efficient data entry and the level of a display unit for efficient viewing by a seated operator. Thus, some artifice or mechanism is required to increase the level of the display unit to a better viewing height. Moreover, since some artifice or mechanism is required, it is economically expedient, from a supplier standpoint, to provide a single adjustable base to accommodate the differences in the stature of operators rather than a series of bases of graduated heights. Most video display bases allow side-to-side swiveling and forward to back tilting. Additionally, for ease of viewing, a height adjustable base should provide the feature of maintaining a fixed screen orientation relative to the operator and the supporting surface throughout all height adjustments.
Federal Republic of Germany Offenlegungsschrift No. 2,847,135 published May 8, 1980 and assigned to Nixdorf A. G. shows, a data display device mounted upon one type of height adjustable base. This known height adjustable base has a weighted, stationary part and a turnable platform part which is locked into the weighted stationary part, as shown in FIG. 6 of Offenlegungsschrift No. 2,847,135. The turnable platform provides side-to-side swiveling. On the rear of the turnable platform is a hinge. This hinge connects the turnable platform with a height adjustable arm. The hinge and arm are spring loaded to counterbalance the weight of a data display device when it is mounted in its operating position. At the end of the height adjustable arm is a tilting mounting bracket for attachment to the data display device. A helical screw pivots the tilting bracket to the operator's desired orientation. The height adjustable arm has two main rods, one on each side of the hinge, and two auxiliary rods, each associated with a respective main rod. The main rods support the weight of the data display device, while the auxiliary rods tilt the mounting bracket in order to maintain a constant orientation of the face of the data display with the horizontal throughout all height adjustments.
The problem of this known design is that a heavy base which projects in all directions, is necessary in order to provide stability during a swiveling of the platform. It is not surprising, therefore, that this known height adjustable base is large in diameter and circular in shape. But, this means that the base inherently occupies a large amount of workspace. Moreover, this known device, because of its large size and substantial weight, is manufactured substantially of metal components which leads to high material and high assembly/manufacturing costs.
Another known height adjustable base is described in Document 880151-01B published December 1985 by Wyse Technology and has been sold by Wyse also. The Wyse base has a tilting and swiveling platform at the top of a pair of parallel, height adjustable arms. If the center of gravity of the data display is substantially positioned over the pivot point of the swiveling platform, then the height adjustable base and the data display will remain stable as the data display is moved. Because of the stability achieved by placing the swivel mounting atop the height adjustable arms, the sides of the base portion can be made smaller than the device known from Nixdorf A. G.
The problem with Wyse height adjustable base is the demanding physical stresses that the major components are subjected to in order to provide the somewhat limited range of height adjustments permitted by the design. The height adjustable base of Wyse adjusts from a minimum of just over three inches to a maximum of over ten inches to the top of the tilt and swivel platform. This adjustment range of seven inches exceeds the range necessary to compensate for differences in the heights of seated operators, and, therefore, makes unduly stringent demands upon the component design.
The height adjustable base of Wyse uses a torsion spring to counterbalance the weight of the adjustable arms, the tilt and swivel platform, and the display. Because of the range of motion, i.e. heights, through which the torsion spring must provide a counterbalancing force, the torsion spring must be very strong. Furthermore, to prevent too much stress in one area, the torsion spring is fitted with a force spreading cylinder and cap mechanism. The inner arm of the parallel pair is the one which is spring loaded. Spring loading the inner arm of the parallel pair reduces slightly the amount of counterbalancing force required by slightly reducing the distance between the torsion spring and the weight of the tilt and swivel platform and the display mounted thereon. The outer arm of the pair is not spring loaded and is included in order to keep the orientation of the tilt and swivel platform constant throughout all height adjustments. This design of Wyse places a substantially large counterbalancing spring mechanism on the inner side, i.e. beneath, the outer parallel arm. Thus, in order to accommodate the counter-balancing spring and the spring mechanism, the device of Wyse necessarily mounts the hinges connecting the inner arm and the outer arm to the base in a relatively high position from the bottom of the base. The result of this design configuration is the limited minimum height of adjustment which the device exhibits.
Besides the problem of a limited minimum height, the design of Wyse additionally has a cost problem. In order to have sufficient strength to provide a counterbalance throughout all height adjustments, the torsion spring and the numerous components associated therewith are of an all metal manufacture. These components, therefore, have a higher cost to manufacture and assemble than is desirable.
Another height adjustable base has been sold by Telefon AB L M Ericsson, Stockholm, Sweden. An illustration thereof appears in the March 1985 issue of BYTE on page 47. It can be seen from this illustration that this configuration is substantially similar to that of the Nixdorf A G base, with substantially similar problems of size and cost.
Thus, it is an object of this invention to provide a compact height adjustable base for a display that does not take up a lot of workspace.
It is another object of this invention to provide a compact height adjustable base that adjusts from a low minimum height to a height which compensates for the differences in the stature of seated operators.
It is a further object of this invention to provide a cost effective, inexpensive to manufacture, and easy to assemble height adjustable base for a display.